So my adept builders all get to about a half inch of the end mark and stop progressing skill-wise. They never get to Master. Also, I'm constantly sending my builders back to fix the hut (that's already fine, mind you) because there is nothing else for them to build to gain skills. Anyone else have this problem? Is this why they aren't mastering anything?

There are many discussions about that, along with suggestions for how to make progress. Just use the forum search function and search for master.

I had that issue too, but with trying to get Master Farmer, but overnight one guy finally did get it. THe others who seem to be at the same level as him, still don't say Master Farmer though. I keep making them fish!

I've found that some individuals take a lot of time to gain experience, sometimes as a general rule and sometimes in specific skills. The general slow learners who are not fooling around but actually do their work are probably not too bright and I do not consider them as candidates for esteem elders. Those who take long time in specific skills, for example building although they are average or even good at farming, probably do not like the task or are uninterested in it.

I have a wonderful guy who likes work - he seldom takes any timeouts - but he is a slow learner unfortunately. Otherwise I might have had a very young esteemed elder in my tribe. It's a pity!

the villagers likes and dislikes affect what they do, and how quickly they learn

however, there are unknown preferences that you cannot see that also affect their performance

eyeshigh has to be correct. I had one guy that had no likes or dislikes when I started my last village and I put him to work as a builder. He easily became a master builder (course, there is stuff to work on at the beginning) without me ever having to pick him up and plop him back on the building like most of them. Then I started him farming and I had to constantly drag him away from "fixing the huts" back to farming. Eventually he mastered that. He fathered a daughter whom I put to work building as soon as she was old enough. Everytime I checked on him, he was trying to help his daughter. Next, I put him at the research table and he again was constantly trying to help his daughter or "fixing a hut". He did become an Esteemed Elder, but not until he was 62.

I have the same problem. A guy just died who should have made master after two days of building a hut and a hospital, and never made master. this is after days of having him build. His bar stopped increasing, but another one who was younger and had worked less at building got master. I'm very frustrated.

yh i dont no how to get master builder so he can clear the vines
i have the 3rd science to clear the vines but not the builder, plus fixing the huts aint getting him up help!

Science is not the tech you need to clear the vines. You don't need a master builder

I am having this same problems with my villagers.None of them want to progress enough to become masters.